Electric heating element.



y A. H. HAPPE & w. 1. KEEP. ELECTRIC HEATING ELEMENT.

APPLICATION FILED JUNE 17. 1915.

1,174,252. I Patnted Mar.7,1916."

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THE COLUMBIA PLANOGRAPH c0 WASHINGTON. D. c.

'A. H. HAPPE'& W. J. KEEP.

ELECTRIC HEATING ELEMENT.

APPLICATION FILED JUNE 11. 1915.

Patented Mar. 7, 1916.

3 SHEETS-SHEET 2- THE COLUMBIA PlAyOuRAPu 110., WASHINGTON, D. C.

A. H. HAPPE & W. i. KEEP.

ELECTRIC HEATING ELEMENT.

APPLICATION FILED JUNE n, :915.

1,174,252. I Patented Mar. 7,1916.

3 SHEETS-SHEET 3- l E J I y EQW TWP appe, zfpmww 1 William J- keepy THE COLUMBIA PLANOGRAPl-l c0., WASHING-EON, n. c.

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ARTHUR H. I'IAPPE AND WILLIAM J. KEEP, OF DETROIT, MICHIGAN, ASSIGNORS TO THE MICHIGAN STOVE COMPANY, OF DETROIT, MICHIGAN, A CORPORATION OF MICHIGAN.

ELECTRIC HEATING ELEMENT.

Specification of Letters Patent.

Patented Mar. 7, rare.

Application filed June 17, 1915. Serial No. 34,565.

heating elements and more particularly to structed with a view to securing maximum heat delivery with a minimum warplng action, and with the parts thereof assembled whereby the core winding or element, which is the only destructible part thereof, can beeasily and quickly removed and another winding element substituted. The armored element is self contained andcapable of operating as a single element or of being associated with other elements to form a grid or heating surfaceof a required area.

When the armored. element is used in connection with the cooking top of a range, its size and shape are conducive to close arrangement in a grid with its wiring fully protected from anything that may boil over on the range. Should it become impaired, however, any armored element can be bodily removed, repaired and replaced.

The armored element possesses many characteristics that will be apparent as the structural details are reviewed, and reference will now be had to the drawings, wherein Figure 1 is a perspective view of an armor case; Fig. 2 is a similar view of an upper sheet of insulation; Fig. 3 is a similar view of aresistance heating element; Fig. 4 is a similar view of an intermediate sheet of insulation; Fig. 5 is a similar view of 'a sectional blade contact conductor, or member;

Fig. 6 is a similar view of a support of insulation; Fig. 7 is a similar view of a lower sheet of insulation; Fig. 8 is a similar view of a retaining pressure plate; Fig. 9 is a similar view of wedging cleats or bars; Fig.

10 is a longitudinal. sectional view of the armored heating element showing all the parts illustrated in Figs. 1 to 9 inclusive, assembled; Fig. 11. is a cross sectional view taken;

on or about the line XI-XI of Fig. 10;

inside surface of the case.

Fig. 12 is a perspective view of a portion of the resistance heating element shown in Fig. 3, showing a connector partly installed; Fig. 13 1s a side elevation of the armored element forming part of a grid for an electric cookmg range; Fig. 14 is a plan of a boiling grid partly broken away; Fig. 15 is a cross sectional view of a portion of the grid taken on or about the line XV-XV of Fig. 13; Fig. 16 is a perspective view of a spring clip connector; Fig. 17 is a plan of the cooking top of an electric range partly broken away;

Fig. 18 is aplan of an oven or boiler grid partly broken away; Fig. 19 is a longitudinal sectional view of the same partly in elevation taken on, or about the line XIXXIX of Fig. 18; Fig. 20 is a cross sectional view taken on or about the line XX-XX of Fig. 18; Fig. 21 is an enlarged longitudinal sectional View of an armored tandem element adapted for an oven or broiler grid, and Fig. 22 is a diagrammatic view illustrating the tandem arrangement of the armored element.

In describing our invention by aid of the views above referred to, it is thought best to refer to the manner of assembling the parts of the armored element, describe each part in its order, and then consider the element as associated with other elements in formingthe grids for an electric cooking range.

The armored element comprises a metallic box shaped case 1, having end walls 2 and longitudinal side walls 3, said side walls having oppositely disposed inclined slots 41 with the inclination of the slots of one wall the reverse of the slots of the other wall. In this armor case is placed an upper sheet of insulation 5, as shown in Fig. 2, said sheet of insulation covering the whole flat Placed against this upper sheet of insulation is a resistance heating element, as shown in Fig. 3, said element comprising a flat core of insulation 6, such as mica, said core having each end thereof provided with a set of openings 7. Wound upon the core is a resistance ribbon or wire 8 having the ends thereof extending contact to insure a positive electrical connection. The connectors 10 are made of thin nickel or other material of high heat resistance and said connectors are bent inwardly upon the under side of the element and formed with depending positioning tongues 11. The element is smaller than the inside of the armor case 1 to maintain its edges out of contact with the walls of the case and thus prevent short circuits.

An intermediate sheet of insulation 12, shown in Fig. 1 is now placed against the resistance winding with the ends of said sheet of insulation extending between the connectors 10 and the end convolutions of the winding. The sheet of insulation 12 is the same width and length as the upper sheet of insulation 5 and has its ends provided with rectangular notches 12 the same width as the connectors to provide clearance for the connectors. In this manner the sheet of insulation 12 can cooperate with the sheet of insulation 5 in laterally centering the resistance winding in the armored case.

Next to the intermediate sheet of insulation 12 is placed a sectional blade contact member, comprising blade sections 13 and a filler section 14 (which, by extending the blade sections, may be left out). he blade sections 18 are duplicates turned end for end, each having the inner end thereof slitted and the material between the slits bent down to form a blade 15. The sections 13 and 1.4L are provided with eyelet openings 16, best shown in Fig. 5, and the sections are held in position by a support 17, in the form of a sheet of insulation shown in Fig. 6. This sheet of insulation has openings 18 adapted to register with the openings 16 and receives eyelets 19. The sheet of insulation 17 also has oblong openings 20 providing passage for the blades and the positioning tongue 11 of the terminals 10. With the positioning tongues 11 extending into the oblong openings of the support 17 the resistance heating element is prop erly sandwiched between the upper and intel-mediate sheets of insulation 5 and 12, and with the edges of these sheets engaging the walls 3 of the case 1, it is impossible for the resistance heating element to accidentally shift and contact with the walls 3 of the case.

On the insulation support 17 is placed a lower sheet of insulation 21 corresponding in size to the upper sheet of insulation 5. The lower sheet of insulation 21 has oblong openings 22 providing passage for the blades 15 and the positioning tongues 11 and said sheet of insulation 21 insulates the eyelets 19 relative to a metallic retaining pressure plate 23 which is neXt placed in the case. This retaining plate corresponds in area to the case 1 and has large rectangular openings 24 providing clearance for the blades 15 and the positioning tongues 11. To hold this retaining plate within the case a plurality of wedging cleats or bars 25 are employed. These wedging cleats are placed in the inclined slots at of the walls 3 and swung or rotated to force and bind all of the parts shown in Figs. 2 to 8 inclusive in the case shown in Fig. 1. Each wedging cleat or bar contiguous to the ends thereof has a depressed portion or protuberance 26 engaging the inner sides ofthe walls 3 and preventing accidental displacement of the cleats after having been properly seated. In rotating or swinging the cleats into position the ends of the cleats ride up on the inclined walls of the slots 4 and become wedged therein, said cleats bringing suilicient pressure to bear upon the metallic retaining plate 23 as to bind all of the parts in correct relation within the case 1. The slots may be made parallel to the surface of the case in which instance an outside pressure is brought to bear at various points on the pressure plate when the cleats may he slipped in and will hold when the outside pressure is removed.

To prevent an armored element from being tampered with or disassembled without detection, we fill the slots 41 with a cement of high heat resistance and of a color similar to the armor case. This cement is designated 4* in Figs. 10 and 11.

lVith the various parts assembled as shown in sections, Figs. 10' and 11, it is to be noted that the blade sections 13 of the blade member have a full contact with the connectors 10 and by placing the ends of the intermediate sheet of insulation 12 between the connectors and the end convolutions of the resistance winding, an electric current is caused to pass through the end convolutious, thereby utilizing the complete winding for heating purposes.

Considering now the armored heating element as a component part of a range heating grid, such as can be advantageously used in the cooking top of the electric cooking range disclosed by an application filed Dec. 26, 1914, Serial No. 879,215, in the name of l/Villiani J. Keep, reference will be had to Figs. 13 to 17 inclusive. The grid comprises a rectangular frame having flat apertured bars 27 connected by bridge pieces 28 and these bridge pieces are connected by supports 29 in parallelism with the bars 27. but in a higher plane. The upper edges of the supports 29 are provided with sets of spacing lugs 30. These lugs are adapted to extend into the case of an armored element, against the end walls 2 of the case and correctly position the armored heating elements in parallelism upon the supports 29. We attach considerable importance to this manner of mounting the heating elements, insomuch that the elements are not fastened 'best shown in Fig. 13.

'inwardly projecting brackets Connected to the aperturedbars 27 of the frame by screw bolts 35, nuts 36, and washers of insulation 37 are a plurality of 38. The brackets 38 are thoroughly insulatedfrom the bars 27 and said brackets extend inwardly beneath the supports 29 below the ends of the heating elements. There are two brackets for each armored heating elepreviously described.

ment and said brackets are provided with spring clip connectors adapted to receive the blade contacts 15 of the heating element. Each spring clip connector is in the form of two resilient contact arms 39 swiveled on the brackets, and between which a blade contact is adapted to extend and establish an electric circuit through a heating element, a set of brackets and screw bolts holding the brackets. The screw bolts 35 are connected in series by connectors 40 and lead wires 41 are connected to the terminal screw bolts 35, as shown in Fig. 17. y

The resilient spring clip connectors permit of expansion and contraction of the heating elements and no weight whatsoever is sustained by the brackets 38, as the walls 3 of the armored heating element cases restupon the supports 29, consequently the heating elements are capable of. sustaining considerable weight.

In operation, a current flows through the blade contacts 15 of each element, through connectors 10 and through the resistance winding 8. All of these parts are thoroughly insulated from the case 1, as are the retaining plate 23, cleats 25, eyelets 19 and metallic parts not intended as conductors.

In Figs. 18 to 22 inclusive there is illustrated a tandem heating element and by the novel construction resorted to we have found that heating elements can be made of considerable length and advantageously used in various structures. The heating element is armored and is constructed upon the same principle as the armored heating elements In this instance, however, we use channel cases disposed in longitudinal alinement and devoid of end walls. In each case and insulated therefrom is a heating element 51 and connecting the -heatingelements is an intermediate contact upon the heating elements.

of the side and rear bars 59 and 60.

conductor 52 extending out of one case into the other. Associated with said contact conductor are end contact conductors 53 which extend out of the cases and have angularly disposed apertured terminals 54. The contact conductors 52 and 53 are riveted or otherwise connected to a sheet or sheets of insulation and are retained in en gagement with the heating element 51 by a sheet of insulation 55 and a pressure plate 56, said pressure plate being held within the cases 50 by transverse cleats or bars 57. With the pressure plate 56 of a length greater than the combined length of the cases 50, the pressure plate serves in both cases and constitutes a connecting medium between the cases, whereby the armored element can be easily handled. The pressure plate 56 has depending ends 58 constituting positioning lugs when the armored element is used in connection with an oven or broiler grid, such as illustrated in Figs. 18 to 20 inclusive.

An even or broiler grid comprises channel side bars 59, a channel rear bar 60, a solid front bar 61, and an inverted channel brace 62 connecting the front and rear bars of the grid The channel side bars and the brace 62 support the armored tandem heating elements. The ends of the cases 50 of each element rest upon the brace 62 andthe inner side walls of the channel bars 59. The depending positioning lugs 58 of the pressure plate 56 of each element engage the inner sides of the inner walls of the bars 59, as best shown in Fig. 19, thereby correctly positioning the elements. With the outer ends of the cases 50 open, the terminals 54 of each heating element can extend into the channel side bars 59 and some of the terminals 54 are provided with connectors 63 placing the heating elements in series. The channel side bars 59 afford protecting conduits for leading in wires which are carried through a hollow trunnion 64 forming part of the rear channel bar 60.

The channel side bars 59 are provided with covers 65 and the rear channel bar with a cover 66, the ends of which overlap the ends of the covers 65. The inner edges of the covers have extensions or branches 67 overlying the ends of the heating elements, and all of said covers and extensions thereof are shaped to deflect and shed liquid or foreign matter that may be deposited The covers 65 and 66 are retained in position by swiveled clamps or buttons 68 and 69, the former being on the front bar 61 and the latter upon webs or corner pieces 70 at a juncture A further liquid shedding cover 71 is placed over the confronting ends of the cases 50 of the heating elements, said cover having one end ton 74% on the front bar 61. lVe attach considerable importance to this central cover as it protects the confronting ends of the cases and prevents liquid or foreign matter from entering the ends of the cases.

In connection with the single and tandem heating elements we have discovered a metallic armor which is free from injury by constant and ordinary use, thereby increasing the longevitv of elements, and this discovery forms the subject matter of an application filed June atth, 1915, Serial No. 32,107 in the name of lVilliam J. Keep.

e attach considerable importance to the compactness of the armored heating element, the manner in which it is supported, and the ease with which it may be installed. This is an important factor in the manufacture of electric cooking ranges and the heating elements herein described are a salient feature of the Keep electric cooking range heretofore referred to.

l ve find that out of curiosity our armored elements have been dismounted and reassembled with some of the sheets of insulation left out, probably because their useful.- ness was not apparent. We wish to have a central station man or a competent electrician replace an element if necessary, but our guarantee does not cover displacement bv incompetent or curious persons. We have therefore made a cement of high heat resistance and of the color of the armor case which we press into the slots and which hardens in a few hours and acts as a seal.

hat we claim is 1. A case, a heating element Within the case and insulated therefrom, and transverse cleats wedged in the side walls of said case for retaining said elements therein.

2. A case having side walls provided with inclined slots. a heating element in said case and insulated therefrom, transverse cleats having the ends thereof in the slots of said case walls, and means on said cleats adapted to prevent displacement of said cleats relative to said case.

3. A case, a core in said case, a resistance ribbon on said core, connectors at the ends of said ribbon. a support of insulation in said case. blade sections carried by said support of insulation and contacting with said connectors. retaining plates in said case. and means engaging in the walls of said case adapted to hold said retaining plates in said case with the above mentioned elements under pressure therein.

l. Av case, a core in said case, a resistance ribbon on said core. a retaining plate in said. case provided with openings,blades extending through the openings of said retaining plate, and connectors between said blades and the ends of said resistance ribbon.

5. In a case, a core, a resistance ribbon on said core, a retaining plate provided with openings, blades extending through the openings of said retaining plate, connectors between said blades and the ends of said resistance ribbon, means transversely of said retaining plate to hold the above mentioned element under pressure in said case.

6.1n an armored heating element for electric cooking and heating grids, acase, a resistance winding in said case and insulated therefrom, a retaining plate in said case, blade contact members between said retaining plate and said resistance winding insulated from said retaining plate and having electrical connection with the ends of said resistance winding. and detachable means adapted to hold said retaining plate in said case.

7. In an armored element for electric cooking and heating grids, a case composed of an inverted box with slots in its side, a heating element consisting of a wire wound on a core of insulation, insulation between the element and said case, a pressure plate in said case pressed against the insulation and the element, and cross clamping bars engaging in the slots of said inverted box adapted to retain said pressure plates therein.

8. An armored electric heating element for a range grid composed of a metal case having slots in its depending sides, a sheet of insulation on the inside of said case, the heating element having a winding positioned equidistant from the wall of said case, a sheet of insulation against the winding of said element, connectors bent over said last sheet of insulation, metal conductors fixed on a support of insulation and pressed against said connectors, a sheet of insulation, a pressure plate, and bars in said slots to clamp all parts together in said case.

9. In an armored electric heating element for a range grid, a case, an insulated element in said case, a. pressure plate fitted in said. case, and bars holding said pressure plate in said case and extending through the walls thereof.

10. An armor for a heating element of a grid range. comprising a case. a heating element in said case, means for closing said case. and a seal of heat-proof cement for said closing means adapted to show said case has been opened.

11. In a range, a case for a heating element thereof, a heating element in said case. said case having slots in the walls thereof adapted to accommodate closing means for said case, and a seal of heat proof cement in said slots by which tampering with the closing means of said case may be detected.

12. Armored elements placed end to end, rigid metallic conducting pieces connecting the confronting ends of said armored elements, and covers for such metallic conducting pieces.

13. A heating element for electric cooking and heating grids, comprising cases disposed end to end, a resistance winding in each of said cases, means common toall of said cases for maintaining said resistance windings under pressure in each case, and a cover for the confronting ends of said cases.

14. A heating element comprising cases disposed end to end, a resistance winding in each of said cases and insulated therefrom, said resistance winding having projecting contacts, a cover for the confronting ends of said cases, and covers for the projecting contacts of said resistance winding. I

15. A heating element composed of windings disposed end to end, a rigid fiat connector for the confronting ends of said windings, contacts projecting from the outer ends of said windings, independent sheets of insulation connecting said connectors to said contacts, and means throughi out the length of said element confining said connectors and said contacts under pressure;

16. Heating strip elements placed end to end, a metallic armor for said elements, and metallic connectors Within said armor connecting the confronting ends of said elements.

17. A heating element for electric cooking and heating grids, comprising elements composed of resistance windings disposed end to end, connectors at the ends of said resistance windings, a case for said elements, and means within said case common to said elements for maintaining said resistance windings under pressure.

18. A heating element composed of combined resistance windings disposed end to end, connectors for said resistance windings, projecting contacts for said element, independent sheets of insulation connected to and maintaining said connectors and contacts in a plane parallel with said resistance windings, and covers confining said resistance windings and said connectors.

In testimony whereof we affix our signatures in presence of two witnesses.

ARTHUR H. HAPPE. WILLIAM J. KEEP.

Witnesses:

ANNA M. Donn, KARL H. BUTLER.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents, Washington, D. G. 

